1. Technical Field
The present invention relates generally to water filtration and more specifically to systems and methods of filtering water from decorative ponds and fountains.
2. Discussion of the Related Art
Decorative ponds and fountains have long been popular as part of the landscape of private homes, commercial buildings, public gardens, and parks. Many times, such decorative ponds support an array of aquatic plants and also a variety of wildlife such as fish, frogs, foul, and the like. For example, many modern decorative ponds are stocked with Koi, a rare and beautiful fish with oriental origins. The water in decorative ponds, and especially ponds that support wildlife, must be cleaned and filtered continuously in order to remove solid contaminants such as animal waste and also to prevent the buildup of ammonia, nitrite, and other chemicals that can be harmful to fish and plants.
Filtration systems for cleaning the water from decorative ponds have been available for many years. Early filtration systems generally included a tank at least partially filled with sand. In such systems, known as xe2x80x9csand filters,xe2x80x9d pond water is circulated with a pump through the tank and thus through the sand bed therein and back to the pond. As the water passes through the sand, it is filtered and cleaned and certain chemicals are removed from the water by bacteria that tend to develop and thrive in the sand bed.
While sand filters have been used successfully for many years to filter ponds as well as swimming pools and other bodies of water, they nevertheless have numerous inherent problems and shortcomings. One problem is that sand filter tanks must be relatively large in order to hold a sufficient amount of sand to filter a given volume of water. Further, since sand is more dense than water, the sand bed naturally rests on the bottom of the tank. Unfortunately, solid waste filtered from the water also tends to sink and thus progressively collects in and clogs the sand of the bed. Backwashing, which involves circulating water through the filter in a reverse direction, can dislodge and wash out some of the clogging material. However, since this material must be pumped upwardly out of the sand bed against the force of gravity to remove it from the tank, a substantial amount of material can be left behind. Further, the irregular surfaces of the millions of grains of sand in the sand bed tend to hold the waste material and form clumps of waste and sand, which tend not to be dislodged and washed away during backwashing. As a result, sand filters tend to become clogged frequently, which requires expensive, time consuming, and messy disassembly and manual cleaning. For these and other reasons, sand filters have been used less and less over the years.
More recently, sand filters have been replaced by a filtration system known as a xe2x80x9cbead filtration system.xe2x80x9d A bead filtration system generally comprises a tank filled not with sand but with a filter media formed by millions of small generally spherical plastic beads. The beads are positively buoyant and thus, unlike sand beds, the filter media floats in the top of the tank when the tank is filled with water. Generally, pond water is circulated from the bottom portion of the tank, through the filter bed formed by the floating bead filtration media, and out the top portion of the tank back to the pond. Just as with sand filters, as the water passes through the filtration media, small solid contaminants become trapped in the media and beneficial bacteria living on the surfaces of the small beads consume and neutralize harmful chemicals in the water.
The advent of floating bead filtration systems successfully addressed some of the problems with traditional sand filters. For example, larger or heavier pieces of solid waste that would clog a sand bed tend to sink directly to the bottom of the tank and away from the filtration media in a floating bead system. Furthermore, backwashing a floating bead filtration system to clean the filter media generally is significantly more effective than backwashing a sand filter. This is because, among other things, solid waste that is dislodged from the floating bead media during backwashing naturally tends to sink downwardly away from the media, where it can be removed easily form the tank with the backwash water. Further, since the surfaces of the beads are not irregular like the surfaces of grains of sand, the solid waste collected in the media during the filter cycle is more easily dislodged during backwashing and does not tend to form resistant clumps. The tendency of the plastic beads to expand very slightly when released from their compacted state during backwashing also tends to release microscopic debris trapped within surface pores of the beads. Floating bead filter media for use in water filtration systems is commercially available from various sources such as the New Jersy based Alvis Corporation.
One floating bead filtration system includes an hourglass-shaped tank with the upper portion of the tank being filled with floating bead filter media. Water is circulated from a pond, through the tank from the bottom to the top, and back to the pond in an xe2x80x9cin linexe2x80x9d fashion. As the water flows through the top portion of the tank, it is passes through the floating bead filter media, where it is filtered and cleaned before returning to the pond. In many cases bubbles of air can be injected into the bottom portion of the tank with the goal that the bubbles will float upwardly through the floating bead filter media, where, theoretically, they will agitate the filter media to dislodge trapped waste and debris.
While xe2x80x9chourglassxe2x80x9d bend filter systems are an improvement over sand filters, they nevertheless have had their own set of disadvantages. For example, severe internal clogging is common unless the system is cleaned frequently because of the restricted area of the tank neck, particularly on smaller filters. In fact, daily cleaning to prevent clogging is not unusual for models less than one cubic foot in volume. Perhaps more significantly, hourglass filters provide no convenient access to the filter media. Thus, manual cleaning of the filter media in the event of a severe clog requires disassembly of the system, is wet and messy, and can take hours. Finally, because of their in line operation, hourglass-shaped bead filtration systems do not provide for a rinse cycle after backwashing to prevent dislodged debris from being circulated back to the pond, and can not easily be bypassed during pond medication. For the forgoing and other reasons, hourglass-shaped floating bead filtration systems have not been entirely satisfactory.
In another floating bead filtration system design, the hourglass-shaped tank is replaced with a conventional oval or egg-shaped tank to eliminate the troublesome restricted neck area. Floating bead filter media partially fills the tank and pond water is circulated through the tank from the bottom to the top. In order to enhance the effectiveness of the water flow within the filter, a labyrinth of inflow tubes are arrayed in the bottom of the tank and a similar labyrinth of outflow tubes are distributed throughout the filter media in the top of the tank. Although this design tends to clog less often than the original hourglass-shaped filters and results in a more effective pressure backwash, it has its own set of inherent problems. For instance, the large number of elbow joints in the labyrinth of inflow and outflow tubes forces the water to make many turns as it circulates into and out of the filter through the tubes. Each of the turns introduces flow resistance and can cause energy robbing cavitation in the flow. The result is a substantial amount of overall resistance to the flow of water through the filter and a consequent requirement for larger and more expensive pumps. Further, the outflow tubes of these systems generally penetrate significantly downwardly into the filter media, which allows much of the water to return to the pond after passing through only a portion of the media. This can lead to clogging of the filter media above the median penetration of the outflow tubes and the creation of anaerobic or stagnant areas in the media. Finally, the labyrinth of inflow and outflow tubes within the tank can restrict the movement of filter media and debris during the backwash cycle, thus reducing the effectiveness of backwashing to clean the filter media.
Thus, a need exists for an efficient and effective floating bead water filtration system that successfully addresses the problems and shortcomings of the prior art. Such a system should be inherently clog resistant and should present very little if any inherent resistance to the flow of water through the system. The system should be designed to force all of the water to pass through substantially all of the filter media for complete cleaning and the prevention of stagnant regions and the formation of channels in the filter media. The system should be easy and non-messy to clean without getting wet and should have no internal structures to restrict the movement and agitation of filter media and debris during the backwash cycle. The system should provide for rinsing after backwash to eliminate delivery of dislodged debris back to the pond after backwashing and should provide for bypassing the filtration system to accommodate pond medication procedures. It is to the provision of such a filtration system and to a method of filtration practiced thereby that the present invention is primarily directed.
Briefly described, the present invention, in a preferred embodiment thereof, comprises an improved floating bead water filtration system for filtering and cleaning water from decorative ponds, and particularly ponds that support a population of fish or other wildlife. The filtration system includes a traditional generally oval-shaped tank having an upper portion and a lower portion. Floating bead filtration media is disposed in and at least partially fills the tank. The filtration media floats to and forms a filtration bed in the upper portion of the tank when the tank is filled with water. Preferably, the filtration media fills approximately the upper half of the tank.
A generally tubular water diffuser is disposed in the tank and extends axially from the upper portion of the tank to a position in the lower portion of the tank below the filtration bed. The diffuser is capped at its bottom and top ends and is internally partitioned by a baffle into an upper or return chamber and a lower or supply chamber. An array of supply slots are formed in the wall of the diffuser adjacent its bottom and communicate between the supply chamber of the diffuser and the lower portion of the tank below the filtration bed. Similarly, an array of return slots are formed in the wall of the diffuser adjacent its top and communicate between the return chamber of the diffuser and upper portion of the tank. The second array of slots are positioned such that they reside within the filtration bed near its uppermost extent when the system is in operation.
A supply conduit communicates with the supply chamber of the diffuser for delivering soiled water from a pond thereto. A return conduit communicates with the return chamber of the diffuser for delivering filtered water from the upper chamber back to the pond. In operation, soiled water from a pond is pumped through the supply conduit to the supply chamber of the diffuser. The soiled water then passes through the array of supply slots and enters the lower portion of the tank, from where it flows upwardly through the bed of floating bead filter media, which cleans and filters the water in the traditional way. The filtered water then enters the return chamber of the diffuser through the array of return slots and is delivered through the return conduit back to the pond. Thus, as water circulates through the filtration system, it is continuously filtered and cleaned.
In one embodiment, a multi-port control valve is mounted to the top of the diffuser and is exposed atop the tank. A central return port of the valve is coupled directly to and communicates with the return chamber of the diffuser. The peripherally located supply ports of the valve are coupled to the supply chamber of the diffuser through a set of transfer tubes that extend through the return chamber of the diffuser and through the central baffle into the supply chamber. During the filter cycle, soiled water from a pond is directed through the supply ports of the control valve and travels into the supply chamber through the transfer tubes. From the supply chamber, the water passes into the tank, flows up through the filter media where it is filtered, and enters the return chamber from where it is directed back to the pond through the return port of the valve. During a backwash cycle, the water flow is reversed so that the filter media is agitated and stirred about by the reverse flowing water to release debris and contaminants trapped in the filter media during the filter cycle.
Because of the evenly and symmetrically distributed return slots in the diffuser, the backwash process is particularly effective at cleaning the media and dislodging debris and clumps of debris that may be trapped therein. Further, the combined cross-sectional area of the transfer tubes and the mean free area of the slots in the diffuser are predetermined to be larger than the cross-sectional area of the plumbing pipes supplying water from the pond. Thus, in either cycle, the filtration system of this invention introduces little or no addition resistance to the flow of water beyond that already encountered in the supply plumbing. High flow rates can thus be maintained with relatively little water pressure.
Thus, a water filtration system that successfully addresses the problems and shortcomings of the prior art is now provided. The system eliminates restricted or narrow necks that have caused clogs in some prior art systems and contains no internal plumbing elbows that force the water to turn corners and that introduce resistance in the flow within the filter. Larger or heavier debris fall naturally to the bottom of the tank before encountering the filter media and smaller debris trapped by the filter media is easily dislodged and precipitates out of the filter media during the backwash cycle. The configuration of the central diffuser with supply and return chambers defined within a single central jacket insures even and symmetric flow of water upwardly through the filter media for maximum filtration and the elimination of channeling common with prior art systems. Finally, the location of the return slots in the uppermost extent of the bed of filter media insures that water traverses the maximum volume of filter media for complete and efficient cleaning before being delivered back to the pond. These and other features, objects, and advantages of the invention will become more apparent upon review of the detailed description set forth below when taken in conjunction with the accompanying drawing figures, which are briefly described ad follows.